Rail transportation is commonly used to move people and cargo. Trains of wheeled vehicles often provide a more efficient and timely means of travel than other forms of transportation. Material can be moved solely via rail, or can use rail transportation as a segment within an inter-modal system. Trains generally travel on one or more rails, but can also use other stabilization and directional devices, including electromagnetics.
Trains are powered by one or more locomotives or powered cars, and are usually controlled by an operator. The operator is generally present on board the train, although other arrangements are possible. Propulsion can be provided by a variety of on-board motors, including reciprocating engines, turbines, electric motors, diesel-electric systems or electromagnetic systems. The energy source can be carried on board the train in the form of fuel or battery power. Alternatively, the train can draw power from an external system, such as overhead power lines or an additional electrified rail near ground level.
The operator may control the train by manipulating manual controls or issuing vocal or electronic signals in a cab or a remote location. Trains may have a manual control mode where the train can directly respond to operator inputs regarding commands for applied throttle or other systems. Such a manual control mode may receive operator commands through a hand throttle, or other manual control. The operator may be located within the locomotive, or remotely relative to the locomotive.
As a locomotive operates, it may pull the train along curved track sections. The locomotive may provide tractive power by powering wheels attached to trucks or bogies provided at the bottom of the locomotive. Each truck may have more than one axle, and each axle may include two wheels. As the locomotive negotiates a curved track section, the trucks may pivot relative to the orientation of the locomotive. In a traditional truck arrangement, each axle within each truck may pivot to the same degree as the truck. However, allowing leading and trailing axles to radially steer within each bogie provides efficiency and tractive benefits.
Ahmadian (U.S. Pat. No. 6,006,674) discloses a “Self-Steering Railway Truck.” Ahmadian describes a system for coordinating yaw angles between leading and trailing axles. However, the described system may not operate in conjunction with existing trucks, including those with pedestals. Further, the system described in Ahmadian incorporates a connection between the leading and trailing axles, adding weight, costs and complexity.
Accordingly, there is a need for an improved steering system for a locomotive truck.